1. Field of the Invention
The present invention relates to a process for producing peptide derivatives and salts thereof which are useful as human immunodeficiency virus (HIV) protease inhibitors.
2. Description of the Related Art
Heretofore, various efforts have been performed for the therapy of acquired immunodeficieney syndrome (AIDS) and prevention of infection of HIV by inhibiting the HIV protease. The present inventors have proposed peptide derivatives and salts thereof which inhibit the HIV protease [European Patent No. 490667 (1992)]. The methods for producing said peptide derivatives and salts thereof, however, have been expensive and/or required toxic reagents, for example, Bop reagent.